Semi-Open Loop MIMO CSI Feedback Transceiving
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Solution Overview
Problem
Current Multiple-input multiple-output (MIMO) systems face challenges in supporting high mobility and dynamic interference, with closed-loop (CL) MIMO systems being inefficient for high-speed mobility and open-loop (OL) systems lacking in performance, necessitating a semi-open-loop (OL) MIMO scheme that requires novel channel state information (CSI) transceiving methods.
Innovation Solution
The implementation of a method and apparatus for transceiving CSI feedback in a semi-OL MIMO system, where an evolved Node B (eNB) receives CSI feedback from user equipment (UE) with precoding matrix indexes (PMIs) and determines a modulation and coding scheme (MCS) value, transmitting data modulated based on the CSI feedback using cyclically allocated PMIs, enhancing mobility and interference robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If closed-loop MIMO scheme is used, then data transmission performance is improved, but mobility support capability deteriorates
Solution Approach 1:
The MIMO system is segmented into multiple CSI processes, where each process is configured with specific PMIs. The UE reports CSI feedback for each process independently, allowing the system to combine benefits of different precoding strategies for both performance and mobility support.
Solution Approach 2:
The system employs periodic CSI feedback reporting with different periodicities for different CSI processes. This periodic action allows the system to adapt to channel changes while maintaining structured feedback for semi-open-loop operation, balancing performance and mobility support.
2Adaptability or versatility
If open-loop MIMO scheme is used, then mobility support capability is improved, but data transmission performance deteriorates
Solution Approach 1:
The system merges open-loop and closed-loop characteristics by combining periodic CSI feedback (open-loop style) with PMI-based precoding selection (closed-loop style). This hybrid approach achieves semi-open-loop operation that supports mobility while maintaining data transmission performance.
Solution Approach 2:
The system dynamically selects precoding matrices from codebooks based on reported PMI values while operating in a semi-open-loop manner. This dynamic precoding selection adapts to channel conditions and mobility scenarios, improving data transmission performance without sacrificing mobility support.
3Reliability
If multiple CSI feedback are reported with different PMIs, then diversity gain is improved, but reporting overhead increases
Solution Approach 1:
The system extracts only the essential PMI information from full CSI feedback. Instead of reporting complete CSI matrices, the UE reports compact PMI indices that point to preferred precoding matrices in predefined codebooks, reducing reporting overhead while maintaining diversity gain through multiple PMI reports.
Solution Approach 2:
The system changes the feedback parameter from full CSI matrices to compact PMI indices. This parameter transformation significantly reduces feedback overhead while preserving the essential information needed for precoding selection and diversity gain achievement through multiple CSI processes.
Data Source
AI summary
A method of an evolved Node B (eNB) in a wireless environment is provided. The method includes receiving, from a user equipment (UE), a plurality of channel state information (CSI) feedback respectively corresponding to a plurality of CSI processes that are respectively allocated a plurality of precoding matrix indexes (PMIs), determining a modulation and coding scheme (MCS) value based on the plurality of received CSI feedback, and transmitting, to the UE, data modulated based on the determined MCS value by cyclically using the plurality of PMIs, wherein the plurality of CSI feedback may each include information on a channel quality indication (CQI) as to a PMI allocated to a CSI process corresponding to each of the plurality of CSI feedback.